Two former Parramatta Eels players are accused of harbouring semi-automatic weapons and possessing more than half-a-million dollars in cash after dramatic arrests in Sydney's Centennial Park yesterday.

Det Sgt Steadman said the number of Australians allegedly defrauded by the Latvian nationals, who arrived in Australia on a tourist visa in March, was likely higher than the more than 200 people who had already complained.

"That's the dark figure of crime, I mean how many people were looking for a bargain?" he said.

"That dark figure could be anything."

The pair could also be charged with further offences in other states.

Police will investigate if the man and woman were linked to a wider criminal network and try to trace where the money was going.

Det Sgt Steadman said even though links to an organised crime gang had not yet been established, groups from Eastern Europe were "quite fond of fraud".

He said the investigation had revealed that some of the money had already been sent overseas.

"We don't know where it's gone or what it could possibly be for," he said.

Det Sgt Steadman urged consumers to be on the lookout for fake websites.